Facile Synthesis, Characterization, and Catalytic Behavior of a Large-Pore Zeolite with the IWV Framework

摘要

Large-pore microporous materials are of great interest to process bulky hydrocarbon and biomass-derived molecules. ITQ-27 (IWV) has a two-dimensional pore system bounded by 12-membered rings (MRs) that lead to internal cross-sections containing 14MRs. Investigations into the catalytic behavior of aluminosilicate (zeolite) materials with this framework structure have been limited until now due to barriers in synthesis. The facile synthesis of aluminosilicate IWV in both hydroxide and fluoride media is reported herein using simple, diquaternary organic structure-directing agents (OSDAs) that are based on tetramethylimidazole. In hydroxide media, a zeolite product with Si/Al=14.8-23.2 is obtained, while in fluoride media an aluminosilicate product with Si/Al up to 82 is synthesized. The material produced in hydroxide media is tested for the hydroisomerization of n-hexane, and results from this test reaction suggest that the effective pore size of zeolites with the IWV framework structure is similar to but slightly larger than that of ZSM-12 (MTW), in fairly good agreement with crystallographic data.